Outside rear view mirrors of the type described comprise a mirror foot and a mirror carrier, which is fastenable to the mirror foot so as to be capable of pivoting around a swivelling axis. The mirror foot may in such case be fastened by suitable fastening means to the vehicle and is therefore used to fix the outside mirror on the motor vehicle. The various components needed for operation of an outside mirror, such as a mirror element, an adjusting mechanism, a positioning drive, a heating device and a mirror housing, may be fastened to the pivotally supported mirror carrier.
According to vehicle registration regulations, pivotal supporting of the mirror carrier on the mirror foot is compulsory in modern motor vehicles. The aim is in particular to reduce the risk of injury in the event that a victim of an accident collides with the outside rear view mirrors, which protrude laterally from the body of the motor vehicle. Thus, for example, before an outside mirror is approved a so-called “child's head test” is conducted. During such test, a test specimen corresponding in weight and shape to the dimensions of a child's head is brought into collision with the outside mirror which, in order to pass the test, has to be made to fold inwards by the impact.
Because of the pivotal supporting of the mirror carrier on the mirror foot, conflicting objectives have to be taken into account when designing an outside mirror. On the one hand, the mirror carrier where possible is to be capable of swivelling without great resistance out of its normal position into a folded-in position in order to reduce the risk of injury. On the other hand, while the outside mirror is in operation, the mirror carrier has to be connected as firmly as possible to the mirror foot in order to rule out unintentional displacement of the mirror carrier, especially as a result of vibration. To resolve such a conflict of objectives, U.S. Pat. No. 4,728,181 proposes the use of an elastically supported detent element between mirror carrier and mirror foot. This detent element secures the position of the mirror carrier at a defined swivel angle, which corresponds precisely to the normal position of the outside mirror for observing the traffic behind. When a force directed from front to back or vice versa acts upon the mirror carrier, the detent element disposed between mirror carrier and mirror foot unlatches and therefore allows a substantially resistance-free swivelling of the mirror carrier.
During assembly of the outside mirror, the mirror carrier has to be fastened to the mirror foot in a pivotally supported manner. To solve this fastening problem, it is known e.g. from DE 28 50 164 A1 to provide on the mirror carrier a fastening pin, which is inserted through an eye provided on the mirror foot. After the fastening pin has been inserted through the eye, a fastening screw is attached to the free end of the fastening pin and a spring is placed in between. The effect thereby achieved is that the mirror carrier is preloaded by its fastening pin elastically in the eye of the mirror foot and may be displaced counter to the pressure of the spring in the direction of the swivelling axis. By virtue of the mirror carrier being supported so as to be displaceable axially in the direction of the swivelling axis, it is possible to arrange between mirror carrier and mirror foot detent elements, by means of which the mirror carrier is held in its normal position. As soon as a forward- or rearward-directed force acts upon the outside mirror, this detent element unlatches in that, because of the swivelling motion occasioned by the force, the mirror carrier is pressed upwards in the direction of the swivelling axis and so the detent elements may be moved out of engagement. The drawback of this known design is that it entails a considerable constructional outlay and is relatively difficult to assemble.
From EP 0 846 596 A2 an outside rear view mirror, which is particularly easy to assemble, is known. To simplify assembly, mirror foot and mirror carrier are designed in such a way that the mirror foot is latchable to the mirror carrier. For fastening the mirror carrier to the mirror foot it is possible, for example, to provide radially elastic detent hooks on the mirror carrier, which are latchable to a counterpart detent device provided in the component wall of the mirror foot. The drawback of the outside mirror known from EP 0 846 596 A2 is that the position between mirror carrier and mirror foot is secured not by positive locking, e.g. by means of a detent element, but by frictional engagement. As the friction between the friction surfaces provided on the mirror carrier and on the mirror foot is subject to specific tolerances, reliable adjustment of the friction force acting between mirror foot and mirror carrier is not possible. Consequently, it may happen that the mirror carrier may either swivel too readily, so that it drifts out of the desired position e.g. as a result of vibration, or is too difficult to adjust so that, for example, it fails the “child's head test”.